A hydroformylation reaction, wherein linear (normal) and branched (iso) aldehydes, in which the number of carbon atoms is increased by one, are prepared by reacting various olefins with carbon monoxide (CO) and hydrogen (H2), commonly called “synthetic gas”, in the presence of a homogeneous organometallic catalyst and a ligand was first found by Otto Roelen in 1938 in Germany.
Generally, the hydroformylation reaction known as an oxo reaction is an industrially important reaction in the homogeneous catalyst reaction and various aldehydes including alcohol derivatives are produced and used all over the world through the oxo process.
Various aldehydes synthesized through the oxo reaction may undergo condensation reaction of aldol or the like and may then be converted into various acids and alcohols containing a long alkyl group through oxidization or hydrogenation. In particular, the hydrogenated alcohol obtained by this oxo reaction is referred to as an oxo alcohol. The oxo alcohol is widely industrially used for solvents, additives, materials for various plasticizers, synthetic lubricants and the like.
In this regard, conventionally, since the value of linear aldehyde derivatives (normal aldehydes) among aldehydes that are products of the oxo reaction is high, most of studies associated with catalysts have focused on increasing the ratio of linear aldehydes. However, recently, since products obtained by using branched-aldehydes (iso-aldehyde), for example, isobutyric acid, neopentyl glycol (NPG), 2,2,4-trimethyl-1,3-pentanediol, isovaleric acid and the like, as raw materials, instead of linear aldehydes, have been developed, a great deal research has been continued to increase selectivity of the iso-aldehydes. Accordingly, there is a need for developing catalysts which reduce an N/I (normal/iso) selectivity of aldehyde while exhibiting excellent catalytic stability and activity.